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On the Shipping Information page, when a phone number is provided that has an area code greater than "214", after the "continue on to billing" button is clicked, the following error results: "An error occurred in script 'C:\wamp64\www\effortlessECommerce\effortless_ecommerce_2nd\ex2\html\checkout.php' on line 158: Your order could not be processed due to a system error."
This is because the add_customer stored procedure's "p" (aka "phone") parameter is stored as an "int", and ints have a maximum value of 2,147,483,647. Therefore, a phone number with an area code larger than 214 will fail.
I fixed the error like this:
1) Go to PHPMyAdmin.
2) Click "Procedures"
3) Click the "edit" button next to "add_customer"
4) Scroll down to the second to last row and change parameter "p" from an "int" to a "char".
5) Change parameter "p"'s "length/values" field from blank to "10" (no quote marks).
6) Click "Go" button.
Now it "works on my machine".